Overweight or obese children who lose weight by the time they reach young adulthood markedly decrease their cardiovascular risks, according to a report in the Nov. 17 issue of the New England Journal of Medicine.
Although childhood overweight and obesity frequently persist into adulthood, some children lose weight, often during adolescence, and become nonobese adults. According to this analysis of four large cohort studies that tracked cardiovascular risk factors over two decades, such weight loss dramatically reduces their risk of type 2 diabetes, hypertension, dyslipidemia, and carotid-artery atherosclerosis in young adulthood, wrote Dr. Markus Juonala of the Research Center of Applied and Preventive Cardiovascular Medicine, University of Turku (Finland), and his associates.
"Although the observational nature of our study precludes making clinical recommendations, we hypothesize that reducing BMI [body mass index] in children and adolescents who are overweight or obese could reduce their cardiovascular risk. If this hypothesis is correct, primary care physicians should not take the pessimistic view that once childhood obesity is established, CV risk is also determined, but should recognize that CV risk may be substantially reduced if childhood obesity is successfully treated," said Dr. Juonala and his colleagues in the International Childhood Cardiovascular Cohort Consortium.
The consortium was created specifically to analyze the data pooled from four cohorts – the Bogalusa Heart Study and the Muscatine Study in the United States, the Childhood Determinants of Adult Health study in Australia, and the Cardiovascular Risk in Young Finns study in Finland – in which subjects underwent a baseline assessment of CV risk factors at ages 3-18 years and a follow-up assessment a mean of 23 years later.
"CV risk may be substantially reduced if childhood obesity is successfully treated."
There were 6,328 subjects, including 2,961 males and 3,367 females. At baseline during childhood, the prevalence of overweight or obesity was 12.2%, and that of obesity was 2.3%. At follow-up during young adulthood, the prevalence of overweight or obesity was 54.9%, and that of obesity was 20.7%.
As expected, "our data confirm both the increase in CV risk associated with childhood overweight or obesity and the tracking of adiposity between childhood and adulthood," the investigators said.
A total of 774 subjects had been overweight or obese as children, and 500 of them (64.6%) remained obese as adults. Another 147 subjects had been obese as children, and 121 (82.3%) of them remained obese as adults. In these subjects, overweight or obesity were strong predictors of type 2 diabetes, hypertension, poor cholesterol profiles, and reduced carotid-artery intima-media thickness (a proxy measure for incipient CV disease, since the cohorts were too young to have experienced CV events).
Among 5,554 subjects who had had normal weight as children, 812 (14.6%) were obese as adults. As expected, these subjects who were of normal weight in childhood but became overweight or obese as adults also had adverse CV risk profiles.
However, subjects who had been overweight or obese as children but became nonobese by young adulthood had CV risk profiles similar to those of subjects who had been of normal weight throughout their lives, Dr. Juonala and his associates wrote (N. Engl. J. Med. 2011;365:1876-85).
For example, the subjects who had been normal weight throughout the study and those who had been overweight or obese as children but became nonobese by young adulthood had no increased relative risk for developing type 2 diabetes, whereas those who were overweight or obese in childhood and remained so in young adulthood had a 5.4-fold increase in relative risk for developing type 2 diabetes, and those who were obese in childhood and remained so in young adulthood had a 4.5-fold increase in relative risk.
This study was limited in that the subjects were predominantly white, so the results cannot be generalized to other races or ethnic groups, the authors added.
This pooled analysis was supported by funding for the original four longitudinal cohort studies. Dr. Juonala reported no relevant financial disclosures. His coauthors reported ties to Pfizer, Merck, and AstraZeneca.